That said, I am dubious of the theory that blue signs are easier to see at night. While I wasn't able to find any research that examined blue signs specifically, I did come across one study that showed yellow and white signs are more visible at night than green signs. This suggests to me that blue might not be the best choice for pedestrian safety signs, despite Vienna conventions. This is not to say European sign standards have nothing on their American counterparts. After touring Erope on a quest to learn more about innovative traffic control practices, FHWA officials recommended the US adopt Europe's practice of increasing the saturation of color on traffic signs, regardless of shade.
Interestingly, I also came across a study suggesting that sign-makers have more to worry about that just color choice. This 2001 survey of five countries in the Middle East shows that age, gender, education and income all play a role in how well drivers understand signs. Young women with low incomes and low education levels had more difficulty understanding the intent of roadway signs thant their older, richer male counterparts--though even more disturbing was the fact that just slightly over half the drivers correctly identified all signs. As motorization rates continue to increase throughout the developing world, this could have dangerous implications for roadway safety--particularly of pedestrians.
